Full Idea
If there are no strict psychophysical laws, this rules out reductionism, either by definition of mental predicates in physical terms, or by way of bridging laws.
Clarification
'Reductionism' is the full explanation of the mental in physical terms. An 'anomaly' is a misfit in the current scheme
Gist of Idea
If the mind is an anomaly, this makes reduction of the mental to the physical impossible
Source
Donald Davidson (Davidson on himself [1994], p.231)
Book Reference
'A Companion to the Philosophy of Mind', ed/tr. Guttenplan,Samuel [Blackwell 1995], p.231
A Reaction
But it is by no means clear that there are no psycho-physical laws. How could this be known a priori?